Update AppSec Kit configuration documentation (#4641)

* Update AppSec Kit configuration docs

* Update articles/tools/appsec/advanced-topics.adoc

---------

Co-authored-by: Giovanni Lovato <[email protected]>
Co-authored-by: Petter Holmström <[email protected]>

Author: 3 people

articles/tools/appsec/advanced-topics.adoc

@@ -27,6 +27,8 @@ AppSecService.getInstance().setConfiguration(appSecConfiguration);
 
 You can set or override the following configuration values in the `AppSecConfiguration`:
 
+`vaadinPlatformVersion`::
+The Vaadin platform version that the application is using.
 `appSecRoute`::
 The route of the AppSec Kit user interface.
 `dataFilePath`::
@@ -47,6 +49,10 @@ The boolean value to decide if the npm development dependencies should be includ
 The boolean value to decide if the server push should be automatically activated in the application.
 
 
+=== Vaadin Version
+
+The AppSec Kit requires the Vaadin platform version that is used in the application when getting the Vaadin platform BOM. First, it checks if the `vaadin-core` dependency is present in the application and uses the version of that dependency as the Vaadin platform version. If the `vaadin-core` dependency is not present then it gets the version defined in the AppSec Kit configuration through this configuration option. If this configuration option is not defined then an `AppSecException` is thrown. The version should be defined as a `String`. The default value is `null`.
+
 === AppSec Kit Route
 
 You can configure the route of the AppSec Kit user interface. The default value is `vaadin-appsec-kit`.